SCIENCE AT THE SHINE DOME canberra 6 - 8 may 2009

New Fellows Seminar

Thursday, 7 May 2009

Professor Marilyn Ball FAA
Functional Ecology Group, School of Biology; Head of Ecosystem Dynamics, Research School of Biological Sciences, Australian National University, Canberra

Marilyn Ball graduated from the University of Miami in1972 and then worked with an engineering team specialising in design of regional, urban and local water management systems in Florida and the Caribbean. The lack of design criteria for inclusion of natural vegetation in water management systems led to an awareness of the need for a process-based understanding of relationships between vegetation and environment. To obtain such an understanding, she enrolled in the Department of Environmental Biology at the Australian National University (ANU) from which she received a PhD in 1982 for studies of comparative physiology of carbon gain in relation to water use and salt tolerance in mangrove species. This continues to be a major research interest together with adaptations to temperature stress in temperate evergreens and Antarctic mosses. She was appointed to a tenured position at the ANU in 1990, and today leads a program in functional ecology.

Global climate change will affect the occurrence, severity and distribution of frost, including extreme freezing events. Paradoxically, lengthening of growing seasons due to climate warming can also increase the vulnerability of plants to freezing damage from early or late season frosts. These effects of temperature are amplified under elevated atmospheric CO2 concentration ([CO2]) through at least two processes. First, ice nucleation occurs in leaves at warmer freezing temperatures under elevated [CO2]. Second, the timing of seasonal acclimation to freezing temperatures is altered under elevated [CO2]. Specifically, growth under elevated [CO2] delays acclimation in autumn and accelerates deacclimation in spring. These effects on acclimation are due in part to higher day time leaf temperatures due to lower stomatal conductance under elevated [CO2]. A model was developed to examine the incidence and severity of frost damage to snow gum (Eucalyptus pauciflora) in a sub-alpine region of Australia for current and future conditions using the A2 IPCC elevated [CO2] and climate change scenario. The model shows that potential gains in productivity in response to increasing atmospheric [CO2] and lengthening of the growing season may be reduced by freezing stress in frost prone areas with effects of elevated [CO2] on frost damage being greater in autumn than spring.